Turok 2: Seeds Of Evil

Master code:
Enter BEWAREOBLIVIONISATHAND as a code to activate invincibility, all weapons, unlimited ammunition, and the minor cheat codes. If a multi-player game is started after the code is activated, you may pause game play and select any single player level to allow both players to go through the game together.
Information in this section was contributed by R.P.Conroy, AznKnyt, StarX92, Ken, Elliot Parke, vlad, sjc2000, Ellisdolan, Matthew Olson, bedson, and others.

The code also reveals the final Boss' name (Oblivion) in next game in the series, Turok 3: Shadow Of Oblivion.
Information in this section was contributed by Droideka12.

Opponents have big heads:
Enter UBERNOODLE as a code.

Stick man:
Enter HOLASTICKBOY as a code.

Big hands and feet:
Enter STOMPEM as a code.

Small opponents:
Enter PIPSQUEAK as a code.

Pen and ink graphics:
Enter IGOTABFA as a code.

Blackout mode:
Enter LIGHTSOUT as a code.

Frootie stripes:
Enter FROOTSTRIPE as a code.
Information in this section was contributed by Nike649864.

Gouraud shading:
Enter WHATSATEXTUREMAP as a code.

Juan's cheat:
Enter HEEERESJUAN as a code to place a face on the gold diamonds.
Information in this section was contributed by AznKnyt.

Zach's Cheat:
Enter AAHGOO as a code to turn the diamonds blue with a baby's face.
Information in this section was contributed by AznKnyt.

Jane's Cheat:
Enter JANESWONDERFULWORLD as a code to unlock all graphics-changing cheats.

View credits:
Enter ONLYTHEBEST as a code.

Multi-player invincibility:
Select a level with portals and Scorpion Launchers, such as Teleportastic. Have a second player meet your character at the portal. Stand directly in front of the portal and have the second player take your character's energy out to about ten of fifteen. Remain directly in front of the portal and have the second player shoot your character into the portal with a Scorpion Launcher. The second player will be awarded a kill each time your character passes through the portal. Do not collect any health to keep your character at zero.
Information in this section was contributed by Nike649864.

Multi-player rankings:
The following is a summary of each character in multi-player mode. Good all around characters are Turok, Campaigner, Tal'set or Fireborn. On levels with lava, the Fireborn does not take damage on lava. The Velociraptor should really be selected by an expert player.
Information in this section was contributed by Nike649864.

Turok
Health: 100
Armor: Good
Speed: Average
Health regenerates?: No

Gant
Health: 80
Armor: Good
Speed: fast
Health regenerates?: Yes, once every 5 seconds

Adon
Health: 60
Armor: Heavy
Speed: Fast
Health regenerates?: Yes, once every 3 seconds

Death Guard
Health: 120
Armor: Heavy
Speed: Average
Health regenerates?: No

Endtrail
Health: 100
Armor: Average
Speed: fast
Health regenerates?: No

Fireborn
Health: 100
Armor: Average
Speed: fast
Health regenerates?: No

T2 Team Member
Health: 110
Armor: Good
Speed: Average
Health regenerates?: No

Campaigner
Health: 120
Armor: Heavy
Speed: Average
Health regenerates?: No

Tal'set
Health: 110
Armor: Good
Speed: Average
Health regenerates?: No

Velociraptor
Health: 70
Armor: Light
Speed: very fast
Health regenerates?: No

Monkey (frag tag)
Health: 20
Armor: light
Speed: very fast
Health regenerates?: No

Hint: Two players in single player mode:
Obtain the warp cheat for the desired level to be played. Enter the multi-player options and set the game to no time limit and no frag limit. Begin a regular multi-player match, then pause game play. Return to the cheat option to advance to the desired single player level. Resume the game to play with unlimited health, due to the no frag limit setting. Note: Try to enter warps at the same time or you will be stuck in a black room.
Information in this section was contributed by Nike649864 and jake gereg.

Hint: Play as the monkey in single player mode:
Start frag-tag multi-player game select a character and play as the monkey. Enable the "View credits" code and press Start while they are displayed. Once you return to the main menu, start a new single player game. You will still be controlling the monkey from multi-player mode when game play begins.

Hint: Extra multi-player levels:
Enable the "Master code" then start a Blood Lust or Team Blood game with two or more players. Use the "Warp" cheat to go to any of the six levels in one player mode. These levels are limited -- if a player enters a warp portal the screen will freeze and all players will be warped to the beginning of the level. It is also recommended that the "All Weapons" and "Unlimited Ammo" cheats are used, because no weapons or ammo will be available while playing in this mode.
Information in this section was contributed by Tyler Estes.

Hint: Razorwind stays bloody:
Disable blood in the game options. Begin game play and use the Razorwind. It will return with blood on it.
Information in this section was contributed by Ricky Selinger.

Hint: Gun scope:
Press Right. Note: This does not work on every gun.
Information in this section was contributed by Crazyboy03330.

Hint: Protection from undead:
Disable blood in the game options. The undead hurt you by throwing "gore" - if blood is disabled, they have no weapon.
Information in this section was contributed by Greening Brendan.

Hint: Opening doors:
Killing all the birds in the area may open some doors that have no other way of entry.
Information in this section was contributed by Brian Hernandez.

Hint: See better in dark places:
To be able to see everything in dark places, enabled the "Frootie Stripes" code.
Information in this section was contributed by Patpride57.

Hint: Zoom with scope:
Hold R and press C-Up.
Information in this section was contributed by Crazyboy03330.

Hint: Turn birds into items:
Look up in the first level, use a sniper weapon, such as the plasma rifle or bow, and shoot the birds flying in circles a few times. They will turn into items that fall from the sky.
Information in this section was contributed by Matt Robischon and Kristoffer Jeberg.

Hint: Topless Adon:
Enable the "Gouraud shading" code, then walk into a save point. Adon's skin color will be the same as her top, so she will appear to be topless.
Information in this section was contributed by Tyler Estes.

Hint: Radioactive enemies:
Get the Nuke gun and the Cerebral Bore gun. Spot an enemy at a far distance that can be affected by the Cerebral gun. Get out the Nuke, and as soon as you shoot it quickly change back to the Cerebral Bore gun and fire it. If done correctly, the nuke blows up, the enemy is frozen, then the cerebral bore hits. If the distance was great enough, the bore will not have caused enough damage to kill the enemy, but just enough to awaken it. The end result is an enemy that will spontaneously glow yellow. When you kill it, it will go almost pure black before fading away.
Information in this section was contributed by ismp.

Hint: Enemies fighting each other:
Use the following trick to redirect an enemy's attack to another enemy. The area must be full of enemies or two enemies must be very close to each other. Run away very quickly and they will start fighting each other.
Information in this section was contributed by Tyler Estes.

Hint: Stop mite respawning:
In the mite infested areas of level 5 (The Bugs), just before the queen bugs, you can halt the mites' respawning by lobbing a grenade or a couple of PFMs into their respawning tunnels. You also will get some extra health each time.
Information in this section was contributed by Trevor Davies.

Glitch: Keep enemy alive:
When you kill an enemy, shoot it twice before it disappears. It will make a noise, then bleed. When the blood disappears, shoot it twice again. Continue this procedure and it should not die immediately.
Information in this section was contributed by Laurence Cartwright.

Glitch: Invincibility:
Stand in front of a save portal with very little health. Allow your character to be killed and pushed backwards into the portal in the same attack. Save the game, then return. If done correctly, your character should be at zero health but still be able to play without getting any further damage. Collecting health will negate this effect. Note: Pressing Start has no effect while this glitch is active.
Information in this section was contributed by Nike649864.

Glitch: Delayed jump:
With the correct timing, you can sometimes run off the end of the cliff and jump immediately afterwards.
Information in this section was contributed by SaxxonPike.